My daughter had this maths problem, and quote it from memory:
Given five 4's, separated by the mathematical functions +, -, × and ÷ form
the number 7. The problem also allowed her to use parentheses.
I decided to write an APL expression to solve this, and this is what I came
up with:
* d ← {⍵÷⍺}*
* (↑¨ 7 = ⍎¨ v) / v ← {"4 " , ↑,/ {{⍵," 4 "}¨⍵} ⍵}¨ ,↑∘.,/4 ⍴ ⊂'+-×d'*
Now, this program finds two solutions, which is good enough for me.
However, my program doesn't find solutions that require parentheses.
Problem 1: Can anyone simplify my program?
Problem 2: Can anyone come up with a solution that also checks for
parentheses?
Regards,
Elias
